Casing centering device



July 8; 1952 BAKE? 2,602,512

ASING CENTERING DEVICE FiledFeb. 12. 1949 BY A ATTORNEY S Patented July 8, 1952 UNITE-D STA-TE S PATENT oFF-Ics M V i Q 2502512 p CAS'ING'CEiiTERING 'DEviE" Iieidiri' CQBaker} (J calinga; CaliL, assignor to I Baker Oil Tool s'; Inc Vernon; Cali-L, a corporation' of California AiipliEation'FeBHiari'IZ, m9, seen Nd. 76;14'7' The present invention-relates w devices'j for centering" casing; li'ners"and similar conduits in well bores. j j Q I An' object of the present "invention i topro vide an improved-device for centering -well" co'nduits in well-bores. I

Another object of) the invention"is--'toprovide a device for'centering casing and the like in well bores, which' allows ampleroom for fluid cir culation around' the exterior of 'the casing and through the device. p

Still another-object oft'heinven'ti'on is toprovidearcasing centeringdevice; which ten'ds'to' prevent channeling" of cementitious material depositedbehin'd. the'ca'sing.

A further object 'of "1 the invention 'is to providea centering device for easing and'the like; which is ofsirnple', lightg 'and sturdy construction; and which is comparatively--inexpensiveto' manufacture. j v 7 Yet a further objectof-theinvention is-to pro videa centering collar which mayf be -mounted readily on a well casing, or similar tubular string: Y

Another objector the inventionis to" provide a centering collar-whichwill not tend to interf ere with -the movement of a-"calsing string; on which the" col-laris -mounte'd; in a wen bore.

This inventionpossesses man-y other advantages,and has other'objects which maybe made more c1early"apparent--frorn aconsideration of a form in which itmaybe embodied; This form is shown in the drawings accompanying and forming part of the present" specification. It willnow-be describedindetail; for thepurpose of illustrating'the general principles-of theinvention; but it is to be" understood that-- such detaileddescription is not-to be takenina limiting sense, since the scopeof' the'inventionis best defined by the appen'ded'rclaim'sf Referring to the drawings? Figure l is a side elevation of a vice-mounted one. string; of casing and disposed in'awell bore;

Fig. '2 isa cross-section 2--2 on Fig-1; i

Fig. 3 is an enlarged fragmentary, 1ong'itu-' dinal section taken along the line 33 on Fig.1; Fig: 4 is a side elevation, on fanen'larged scale; of one of the ribs formingpartofthecentering-deviciand r N Fig. 5 is"a View, in-"a single plane; showinga "metallicblank, with 'i-ts upper' andlower mar ginal portions-notched; arid-priorto its-formation into-a collar;

centering de- 7 takenalong the 1111s 50laiin s; (01. 186 -4) As disclosed in the drawings; ajce nteringj de-- vice 'A' is" mounted on a casing, liner; or similar conduit string B positioned af'well'bore' The centering device isd'es'igned to preventzen gagement of the casingBwith-the wall oijthe well bore; in order to retain a suitable annular area completely around the casing, in' whicjh cementslurry' or other cementitious materials may be'deposited: 1 p p The centering device includes a collarfll fl fhave ing upper and lower bent-in portionsprdnf turned flanges l l, l2, which are" provided with notches or slots l3, l4 "atj' spaced pointsjaround their circumferences. The 'uppernotches; "l {are preferably uniformly spaced from "one another, which is alsotrue ofj the"lower notches l lq 7 As disclosedhiiFig. 5, thecollar lemayfbe formed from a single sheet of metal o f prop er gauge or thickness, with the upperlaiiddower ma rginsll', l2 provided with thenotcl les l3,f I51 totherequired depth. After thehlankhasheen suitably notched; it rolled into a cylindrical form and itsends I5'are butt-welded to one" another. Thereafter; the "marginal 'portidnsj;l l;,

I 2 maybe bent inwardlir toprovide' the tapered uppe'randlower'ends. U H

The notches" l I, I2 are so spaced from fone another" on 'both the" upper 'f' and' lower :m alf'EiIlS asjtof'befuniformly spacedf frcni one another when the' 'blank is rclljedinto" a cylindricalfl fornr. Such uniform spacing alsoocciurs between 'the notches" on opposite" sides of the butt-welded joint l5. If desired, thenotches"l l on thelow er margin of theflcollar maybe 'stagge'red'or oif'set with respect to the upper marginal notches I 3,

although thisis not indispensableg v Following formation of the colla V V inturned' fl l I; I 112 ril ra lt j. dina'lly' extending'ribs I one mounted onth terior thereof; These-ribs each have tap 7 upper and lower portions ll,' lg'e t'endingdon tudin'ally outwardly of the collar and notch; as disclosed most clearly-in Fii 1. "Asde were I the collar axis. Each rib is disposed:with1n ;the collar; with its upper portion I received within inclined with "e v scribed above, the lower notches M are offset with respect to the upper notches I3. The extent of this offsetting determines the angle of inclination of the ribs [6 to radial collar planes. Of course, if the upper and lower notches l3, M were in longitudinal alignment with each other, then the ribs [6 could still be inclined by extending them from anuppernotch l3 to a lower notch l4 displaced to one side of the lower notch in alignment with the upper notch.

In view of the inclination of the ribs if, their inner surfaces are preferably curved, or made concave, so as to have surface bearing contact upon a casing B, on which the centering device A is to be mounted. Similarly, the outer surface 2| of each rib may also be curved in convex fashion so as to conform to the curvature ofthe inner wall of the collar It. In view of the fact that the extent of inclination of the ribs 16 to the vertical or radial planes may not be too great,

ample support of the ribs in the collar can be obtained without curving their outer surfaces, by leaving such surface straight. The welding material 19 holds each rib l6 securely to the collar l0. However, if desired, the outer surface 2| of each rib may be curved in the manner above indicated.

' The ribs 16 are uniformly spaced around the circumference of the collar [0, the number of ribs employed depending upon the diameter of the collar and of the casing 13 on which the collar is mounted. As shown in the drawings, by way of example, double the number of ribs may be embodied in the collar than actually illustrated in view of the number of notches l3, I4, but this number may not be necessary. It is, of course, apparent that the number of ribs and notches can be varied without departing from the invention.

The 'complete centering device A is mounted on a casing'section B by sliding it over one of its ends. The centering device may be left free on the casing section, since the inner surfaces 29 of its ribs have an effective diameter slightly greater than the outside diameter of'the casing, which will allow the centering device to slide up and down on the casing, as well as permit rotation of the casing therewithin. The centering device will be limited in its longitudinal movement by the usual couplings D at the upper and lower ends of the casing section on which the centering device is mounted. If it is desired to further limit the extent of lon itudinal movement of the centering device, a suitable stop ring E may be welded on the casing section above or below the centering device, or both above and below the centering device. Usually, it is preferred to place a centering device A immediately above the casing shoe (not shown) and prevent substantial travel of the device away from the casing shoe, in order to insure centering of the shoe, and the casing. joint attached to it, within the well bore. At such point of installation of the centering device, a stop ring E may be welded on the casing a short distance above the centering device.

The centering device A may also be mounted on the casing section and rigidly secured thereto in any suitable manner, as by welding the ends of the ribs l6 directly to the casing B.

As many centering devices as are needed are mounted on the casing string, which is run in the well bore to the desired extent. During running of the casing string in the Well bore, the lower inturned flange l2 and the lower tapered ends l8 of the ribs form guiding surfaces preventing the centering device and easing string from. being stopped or arrested by minor obstructions or restrictions in the well bore. Similarly, the upper tapered flange H and upper tapered ends I! of the ribs [6 provide guiding surfaces for the centering device in the event of upward movement of the casing string in the well bore.

When the bottom of the casing string has reached its intended location, circulating or washing fluid may be pumped down the casing strin for upward passage through the annulus F within the well bore around the exterior of the casing B. Despite the fact that the centering device is bridging the annular space to a certain extent, the washing fluid has ample area for traveling through the annulus, since it can flow within the interior of the collar I0 between the ribs [6, as well as around the exterior of the collar Ill. The space between adjacent ribs is quite substantial, and allows almostunimpeded circulation of the washing fluid through the collar. In addition, the inclination of the ribs [5 to the vertical causes the washing fluid to whirl as it proceeds upwardly through the collar, creating turbulence, which is effective in aiding the proper conditioning of the well bore.

After the well has been conditioned by the circulating fluid, the necessary quantity of cement slurry, or other cementitious material, may be pumped down the casing string B. passing out through the shoe, or other point in the casing string, for upward passage through the annulus F around the casing. Since the collar device A is holding the casing B substantially centered in the well bore and spaced from its wall, a uniform deposit of cement slurry may be placed behind the well casing. As this slurry passes upwardl through the collar In, it is also caused to whirl, or become turbulent, which minimizes, if not eliminates, channeling of the cement slurry, and insures a uniform cement sheath around the well casing.

It is apparent that the casing centering device is of comparatively light and sturdy construction, and inexpensive to manufacture. It can effectively center the well casing in the bore hole; it produces a whirling action on the fluid passing longitudinally along the exterior of the casing; and it is readily guided past any obstructions or restrictions in the well bore, in view of its tapered upper and lower ends.

The inventor claims:

1. A prefabricated casing centering device comprising a substantially cylindrical collar having inturned flanges at either end thereof, said flanges having circumferentially spaced notches therein, and substantially longitudinally disposed ribs within said collar and notches, said ribs being secured to said collar.

2. A prefabricated casing centering device comprising a substantially cylindrical collar having inturned flanges at either end thereof tapering inwardly in opposite directions toward the axis of the collar, said flanges having circumferentially spaced notches therein, and substantially longitudinally disposed ribs withinsaid collars and notches, said ribs being-secured to'said collar.

3. A prefabricated casing centering device comprising a substantially cylindrical collar having inturned flanges at either end thereof, said flanges having circumferentially spaced notches therein, and substantially longitudinally disposed ribs within said collar and notches, said ribs being secured to said collar, and each rib being inclined to a radial plane of the collar.

4. A prefabricated casing centering device comprising a substantially cylindrical collar having inturned flanges at either end thereof, said flanges having circumferentially spaced notches therein, and substantially longitudinally disposed ribs within said collar and notches, said ribs being secured to said collar, each rib being inclined to a radial plane of the collar, the inner surface of each rib being concave.

5. A prefabricated casing centering device comprising a substantially cylindrical collar having inturned flanges at either end thereof, said flanges tapering inwardly in opposite directions toward the axis of the collar, said flanges having circumferentially spaced notches therein, and substantially longitudinally disposed ribs within said collars and notches, said ribs being secured to said collar, each of said ribs being inclined to a radial plane of the collar, the inner surface of each rib being concave.

REUBEN C. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

